Cathode ray tube symbol display system having equal resistor postition control



D 1964 E. D. ORENSTEIN ETAL 3,161,866

CATHODE RAY TUBE SYMBOL DISPLAY SYSTEM HAVING EQUAL RESISTOR POSITIONCONTROL 2 Sheets-Sheet 1 Filed May 11, 1959 TO ANALOG NIZA'HON CI ICU IT6 CHARACTER SELECTION DlGWAL TO AN ALO G INVENTORS. EDWARD D. ORENSTEINBY MALCOLM MACAULAY JM/KW ATTORNEY Dec. 15,

CATHODE RAY TUBE SYMBOL DISPLAY SYSTEM HAVING Filed May 11, 1959 E. D.ORENSTEIN ETAL 3,161,866

EQUAL RESISTOR POSITION CONTROL 2 Sheets-Sheet 2 IN VEN TOR-5T.

EDWARD D. ORENSTElN MALCOLM MACAULAY ATTORNEY United States PatentCATHQDE RAY TUBE SYMBGL DESPLAY SYSTEM HAVING EQUAL RESETOR PGSETKONCONTROL Edward D. Grenstein, Minneapolis, and Malcolm Macaulay, St.Paul, Minn, assignors to Data Display Incorporated, a corporation ofMinnesota Filed May 11, 1959, Ser. No. 812,384 5 Claims. (6!. 340-624)This invention relates generally to high-speed data processingequipment, and pertains more particularly to a system for displayingcoded information in the form of intelligible visual symbols.

The readout and display of coded information in an easily understoodform for ready viewing is not new. While a number of attempts have beenmade to produce a satisfactory symbol generator, such attempts stillleave much to be desired in the way of greater simplicity, rapidity,cost and reliability. However, certain of the prior art devices will bereferred to in order to emphasize to better advantages the attributes ofthe instant invention.

One prior art scheme, for instance, makes use of a metal mask or stencilmounted within a cathode ray tube, the mask containing openingscorresponding to the character configuration to be displayed on thetubes screen. The mask is quite small, being on the order of one-halfinch square, and might possess up to sixty-four separate and distinctopenings if that many alpha-numeric symbols or characters are desired.In producing the desired character, the electron beam generated withinthe cathode ray tube is deflected electrostatically through theappropriate mask opening, and then deflected magnetically to the desiredlocation on the tubes fluorescent screen. Due to the problems involvedin re-focusing and converging the beam between deflections, this methodsrequires a cathode ray tube of considerable length. Furthermore, theelectron gun and the magnetic deflecting yokesassociated with this typeof tube require a number of fine mechanical adjustments. Therefore, notonly is a tube of this character expensive to manufacture, but it isalso diflicult to align for satisfactory operation.

The second method of symbol generation warranting comment at this timeinvolves the scanning of a fluorescent screen with an eltcron beam toproduce a fixed raster, similar to that of a television receiving set,and intensifying the beam upon its reaching certain positions on thescreen. By properly selecting the positions, a series of bright dots canbe made to appear having the desired character configuration. However,this system requires a raster scanning which is very high in relation tothe character display rate. needed having a frequency responseconsiderably higher than the raster scanning rate.

The third method of symbol generation that will be mentioned untilizes aseries of sine and ramp functions in various combinations in order toproduce certain patterns on the face of a cathode ray tube. Thisparticular system is usually limited to symbols which are combinationsof circles, squares and triangles. It is rarely used to generatealpha-numeric characters. Furthermore, it is most adaptable to thedisplaying of very large symbols, for example, several inches indiameter.

One object of the present invention is to provide a system fordisplaying coded information in symbol form, alpha-numeric andotherwise, on the screen of a cathode ray tube with good accuracy sothat the symbols can be quickly recognized.

Another object of the invention is to generate and display the varioussymbols in an extremely short period of time, for instance, on the orderof one to three microseconds per symbol.

Another object is to provide for the display of symbols Also, anunblanking amplifier is having various desired sizes. More specifically,it is an aim of the invention to provide for the supervisory control ofthe symbol size by suitable signals, such as from the output register ofa computer. It is also within the contemplation of the invention toadjust the ratio of width to height of the symbols.

Also, the invention has for an object the varying of the intensity ofthe indicated symbol. As with the preceding object, this may be done viacomputer programming.

A still further object is to provide a display system of the foregoincharacter that lends itself readily to use with a cathode ray tubeequipped with either electrostatic or electromagnetic deflectingcircuits.

Yet another object of the invention is to provide a highly versatilesystem for displaying encoded data in discernible form in which thesymbols may be readily changed. In other words, if a different symbol orcharacter configuration be desired for a given bit of coded information,the invention permits the interchanging of appropriately designed patchboards, or if desired individual plug boards might be employed in whichpotential values could easily be modified to suit specific conditions.The point to be understood in this regard is that the system is notinflexible, instead being susceptible to facile modification wherecircumstances so dictate.

A still additional object is to provide a display system of thecontemplated type that will employ an array of simple digital logicelements that can be easily wired to provide the various discretepotentials used in the functioning of our invention.

Generally speaking, one embodiment of the invention comprises aconventional cathode ray tube in which the electron beam can be movedover the fluorescent face thereof through the application of differentpotentials to its deflection system. Discrete potential signalsrepresena-tive of the coded data are produced by suitably connectedlogic elements and these voltages are applied to the deflection systemin a successive fashion so as to cause the electron beam to beprogressively shifted from one location to another until the desiredalphabetical or numerical symbol has been painted on the screen of thecathode ray tube. Any alpha-numerical character can be quickly produced.To do this, a set of suitable voltages will be selected which whenapplied to the cathode ray tube will cause the beam to traverse theappropriate path for the particular symbol tobe displayed. For adifferent symbol, a different set of voltages will be utilized, althoughcertain of the voltages will of course be repeated in providing thesecond set.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

The invention accordingly consists in the features of construction,combination of elements and arrangement of parts which will beexemplified in the construction hereafter set forth and the scope of theapplication which will be indicated in the appended claims.

In the drawings:

FIGURES 1A and 13 when placed side by side collectively depict aschematic representation of one embodiment the invention may assume, thediagram being largely in block form;

FIGURE 2 is an enlarged front view of the screen of the cathode ray tubewith a typical numerical display pictured thereon; and

FIGURE 3 is a fragmentary view of a portion of the screen shown inFIGURE 2 on a still larger scale in order to illustrate to betteradvantage how a particular numeral is displayed.

Referring now in detail to FIGURE 1, the system there presented forexemplifying the invention includes a computer output register it! ofconventional design in which is stored certain coded information inbinary form. For

the sake of discussion, it will further be assumed that the storedbinary data is representative of decimal system numbers to 7. Hence, forour purposes the following abbreviated conversion table is all that isneeded:

Decimal system: Binary system 0 In the selected situation, the binarysignals from the computer register 10 are fed when called for over three1ines 14, 16 and 18 to a character selection translator 20 typicallycomposed of a number of logical elements wired together so as to producea single output signal for each binary number. However, it is theresponsibility of the translator to deliver such signal to one of eightchannels 22-36. Thus, if the translator receives .binary signals overlines 14 and 18, but not line 16, it knows that the number '5 is to berepresented in the decimal system. Consequently, the output signalproduced by the translator would be applied to channel 32. In order tosimplify the ensuing description as much as possible, and since thenumeral has been mentioned in the preceding paragraph, this particularnumber will serve as a satisfactory illustration. in this regard, eachof the channels 22-36 is shown leading to what will be termed logiccoincidence circuitry denoted in its en- 't-irety by the numeral 38.

Associated with the circuitry 38 is a timing chain device 40, such as adelay line or a string of flip-flops that successively trigger eachother at prescribed intervals. An output signal is produced each timethe device 411 changes state. For our purpose, twenty successive timingsignals will be all that are needed, so the device has been divided intotiming sections Til-T20. The device 4th is triggered into operation by ashort pulse from a resynchronization circuit 42 at the proper moment.Initiation of this action occurs by virtue of a signal transmitted fromthe computer output register 10, or a control register associatedtherewith, over a ready line 414. As the name of the line 44 implies,the register is at that time in readiness for the read-out of binarydata by Way of the lines 14, and 18.

Included in the logic circuit 38 are twenty two-input AND gates 51-70and ten two-input OR gates 71-81), all composed of simple digital logicelements. In order not to unduly complicate the description and also inorder not to encumber the drawing with a multiplicity of lines, onlychannel 32 (the channel denoting the numeral 5 We have selected as aspecific numerical example) has been shown connected to one input ofcertain of the AND gates 51-711, these particular AND gates being 51,52, 53, 54-, 55, 56, 58, 6t), 62, 64, 65 and 68. Other connectionpatterns would be employed for other symbols to be displayed. Thegeneral principles involved will be understood, though, :from adescription of just a single pattern.

The section T1 of the timing device 40 is connected as illustrated tothe second input of the AND gates 51, 53, 55, 64 and 65. Likewise,section T2 is shown connected to the second inputs of AND gates 52, 54,56 and 63. The sequencing role played by the timing device and itsconnection to the various AND gates will become better understood as thedescription progresses.

At the moment it will suflice to explain that whenever there is anoutput from either AND gate paired with a given OR gate, there will bean output voltage signal from that particular OR gate. For instance, ifeither AND gate 51 or 52, these two gates being paired with the OR gate71, emits a signal by reason of the simultaneous application ofenergizing signals to both of its inputs, then the OR gate 71 willproduce an output voltage.

The outputs from the OR gates '71, 72 and 73, it will be noted, areconnected together through three symbol forming resistors 81, 82 and 83;the outputs from the OR gates 74, 7S and 76 are similarly connectedtogether through a trio of additional resistors 84, 85 and 86; theoutputs from the OR gates 77 and 78 are in turn connected to each otherby a pair of resistor 87 and 38, and the OR gates 79 and 80 are by thesame token connected together by resistors 89 and 91 In this way, aplurality of junctions 91, 92, 93 and 94 are provided by which differentpotentials are produced. If the various OR gates 71, 72 and 73 areenergized with, say, minus fifteen volts, the outputs of these digitalelements can be either zero volts or minus fifteen volts. The zero voltslevel will be defined as the 011 state and the minus fifteen volt levelwill be defined as the on state. If, for example, all three OR gates 71,72 and '73 are oil, it follows that the voltage at junction 91 will bezero volts. On the other hand, if all three elements '71, 72 and 73 areon the voltage will be minus fifteen volts. If any one element 71, 72 or73 is on and the other two are off, the voltage at point 91 will be fivevolts. When two elements are on and the third off, the potential insteadwill be ten volts. Consequently, by turning the various elements on and011 in various combinations, the potential at junction 91 can be changedto any four of the listed values, i.e. zero, five, ten or fifteen, forequal ohmic values of the resistors 81, 82 and 83. The same'potentialscan be developed at junction 92 as at junction 91, i.e. zero, minusfive, minus ten and minus fif teen. By the same token, junction 92 canbe readily modified as to its potential. Inasmuch as only threepotential states are needed at junctions 93 and 94, as will be betterunderstood as the description progresses, only two resistors 87, 88 and89, have been employed. With an applied voltage of minus ten volts, itcan be readily seen, it is felt, that when both OR gates 77 and 78 areon the potential at 93 will be ten; if either element is on the voltagewill be five, yet if both are 011 the voltage will be zero. The same istrue for junction 94 in which the state of the OR gates 79 and 80 areinvolved.

The foregoing voltage magnitudes have been utilized in order todemonstrate the discrete voltage units that can be derived with thecontemplated logic scheme made possible with the circuit 38. Thesevalues can readily be multiplied by whatever factor is necessary toprovide the actual working potentials required at the junctions 91, 92,$3 and 94.

The junctions 91-94 supply discrete deflecting potentials for a cathoderay tube indicated generally by the reference numeral 96. As isconvention, the tube 96 is equipped with an electron gun 8 at one endfor generating an electron beam and a fluorescent screen 100 at theopposite end. Also included in the tube 96 is a pair of verticaldeflecting plates 1112, 1114 and a pair of horizontal deflecting plates1116, 108. The description can be somewhat simplified by not showing thefilament and high voltage supplies associated with the cathode ray tube96, so the plate 102 is shown connected to the junction 91 only througha mixer the plate 104 to the junction .92 via a mixer 112; the plate 1%to the junction 93 through a mixer 114, and the plate 108 to thejunction 94 by Way of a mixer 116. The office of the mixers 110- 116 isto cause the electron beam to impinge on certain regions of the screen1110, whereas the smaller potentials developed at the junctions 91-94will deflect the beam to designated areas Within a particular region onthe screen. It might'be pointed out that there is a polarity inversionor reversal that takes place between the junctions 91-94 and thedeflecting plates 1112-1118. We can assume for the sake of discussionthat the inversion occurs within the mixers 110-116, the result beingthat the plates are energized with positive deflecting voltages in thisinstance. To supply the deflection potentials to the mixers 1111'- 116,appropriate information is contained in the computer output register15). Since this control information is in binary form, as alreadymentioned, the binary signals controlling the Y or vertical deflectioncan be transmitted from the register it via a predetermined number ofchannels 118 to a digital-to-analog converter 12.0 which changes thebinary information into usable discrete potentials much in the samemanner as done by the coincidence circuitry 38. By the same token, the Xor horizontal deflection signals are transferred over channels 122 to asecond digital to-analog converter 124. The outputs from these twoconverters 123 and 124 are forward directly to the mixers 110-116 overlines 126, 128, 131i and 132. What the mixers do, then, is to determinewhere the particular symbol to be displayed is to be located on thefluorescent face or screen 106. These various regions have been assignedthe reference numeral 133 and each has a numerical symbol appearingthereon as can be seen from FIGURE 2. Actually, each region 133 issubdivided into smaller areas but more will be said later on concerningthis aspect of the situation.

In some instances, the intensity of the electron beam should be varied,for example, where particular emphasis or de-emphasis of a symbol isdesired. Therefore, it is planned that the computer output register 11contain information to this effect. Four levels of intensity can readilybe achieved with two channels 138 and 14% leading from the register 11}to a digital-to-analog converter 142. A conductor 1455 leads from theconverter 142 to a video amplifier 146 which in turn affects the biasingpotential applied to the control grid of the electron gun 93 within thecathode ray tube 96 via an unblanking circuit yet to be referred to.

Another control that should be mentioned at this time is the control bywhich the size of the symbol being displayed may be changed. Signals forachieving this aim can also be stored within the register 11 and are fedout via single channel 148 to an OR gate 150, the presence or absence ofa signal causing an output or no output, respectively, from this gate.The output side of the OR gate 151 is impressed upon corresponding endsof a plurality of resistors 151, 152, 153, and 154. The other ends ofthese resistors are connected to the junctions 91, d2, 93 and 94 so actto change the potential of these junctions whenever there is an outputsignal from the element 150. In this way, two different sizes of symbolscan be displayed, although further size changes can be effected, ifdesired.

Acting in conjunction with the control mentioned in the precedingparagraph is another control. This control involves the use of aplurality of potentiometers 156, 157, 158 and 159. The potentiometers156, 157 are ganged together at 160 so that they are adjusted in unison;likewise, the potentiometers 158, 159 are ganged together at 162 so thatthey, too, are operated together. Although concerted adjustment of thepotentiometers 156-159 can be used to produce a manual change in thesize of the symbols to be displayed on the cathode ray tube screen 1%,their primary purpose is to vary the aspect ratio. It is believedreadily apparent that adjustment of the potentiometers 156, 157 willchange the potential at junctions 91 and 92. If the setting of thepotentiometers 158, 159 remains unchanged, then only the height of thesymbols will have been modified inasmuch as the junctions 91, 22 are incircuit with the Vertical deflecting plates 162, 1%. However, both pairsof potentiometers can be readily adjusted to whatever ratio of symbolheight to width is desired.

Reference has herein been made to FIGURE 2 and the various regions 1313which have been arbitrarily shown as being twenty-five in number.Attention is now drawn to FIGURE 3 where one of these regions, let ussay the upper left hand one of FIGURE 2, has been subdivided intothirty-five different areas 162. These areas 162 constitute a rectanglehaving seven areas on one side and five such areas along one end. Sincethe electron beam can be initially deflected into this general portionof the screen via specific potentials applied to the defleeting plates102 and 106 by way of the mixers 110 and 114, we need only superimposesmaller discrete potentials on the plates 1G2 and 106, as well as applycertain discrete potentials to the plates 1&4 and 1433 in order to shiftthe impinging electron beam from location to location within thisspecific region. The beam, therefore, strikes certain of the areaswithin the region 133 in successive order, the particular areas impingedby the beam fluorescing and thus displaying the symbol which in theselected instance will be 5. To aid in understanding what relativepotential values at the junctions 91-94 are needed to shift the beamfrom area to area in FIG- URE 3, the coordinates have been assigned thepotentials that would appear at these junctions. The actual potentialsto be impressed on the deflecting plates 192-106 are of course derivedfrom the junction voltages. More specifically, the negative potentialsabove the Zero central horizontal row would be applied to the plate 1112and those negative magnitudes below this row would be applied to theplate 104, relatively speaking. Similarly, the negative potentials tothe right of the central zero column would be impressed on the plate 1%,whereas the negative potentials to the left would be applied to theplate 106. It has already herein been explained that the potentials inthe illustrative embodiment are inverted by the mixers 110-416.

As a further aid in understanding the path taken by the electron beam inpainting the number 5 the various successive positions required to formthis numerical symbol have been labeled with a P and the numericalsufiix indicates the time that the electron beam assumes a givenposition. More will be said concerning the shifting of the beam fromspot to spot when the operation is described.

At this time attention is called to the provision of an unblankingcircuit 164 associated with the electron gun 98. As is customary withcircuits of this type, the circuit 1% normally applies a sufiicientlynegative potential to the control grid of the gun 98 so as to bias thetube 95 to cut-off. However, the unblanhing circuit 164 receives itstriggering signal from the section T1 of the timing device til wherebythe electron beam is turned on. Since, as Will hereinafter be madeclearer, we are desirous of seventeen positions when painting the number5, when the seventeenth position is reached the electron beam should beturned oif again. To eflect this, a separate AND gate 1% is associatedwith the section T17 of the timing device 49, this gate being anded withthe section T17 and channel 32. Its output is connected to theunblanlring circuit 164 and restores it to its normal blanking stateupon completion of a given symbol display.

When the last position has been reached for a particular symbol, aresume signal should, in some instances, be relayed back to the register11 Easy provision can be made for accomplishing this when founddesirable or expedient to do so. For the situation at hand, theseventeenth position is the last so at the same time a blanking signalis delivered to the circuit 154, the AND gate 1&6 can be connected so asto deliver a resume signal back to the computer register 1%). In otherwords, one line 168 connects the output of the gate 166 to the circuit164 and a second line 171) conveys the same signal back to the registerit? so that no time is lost in conditioning the register for a suceedingcharacter read-out.

It will be understood, though, that where a symbol is generated anddisplayed in a shorter period (or longer period) an AND gatecorresponding to the gate 166 would be associated with the appropriatesection of the timing device 4%. For example, in generating the mostsimple number, that is a the gate supplying the dual function of thegate 161? would have one input connected to section T7 and its otherinput to channel Having in mind the foregoing elements and theirorganization with respect to each other in the system, it is believedthat the ensuing description involving the generation and display of thenumeral 5, hereinbefore selected, will provide an adequate understandingof how other symbols can be formed. The particular symbol configuration,of course, is not important to a practicing of the invention.

To facilitate a comprehension of the following description, though, thevarious areas 162 to be traversed in stepwise fashion by the electronbeam have been shaded and denoted by the letter P. Collectively, theseareas 162 constitute one region 133. Each position P is followed by anumerical suflix corresponding with the sequencing provided by thetiming device 49. In other words, when the section T1 is activated itputs out a signal which is applied to the hereinbefore referred tosecond inputs of the three AND gates 51, 53 and 55. Since the channel 32is at this time supplying a sustained voltage signal to what has alreadybeen referred to as being first inputs of these three AND gates, thedesignated gates energize one input of the OR gates 71, '72 and '73. Theoutput voltages, namely minus fifteen volts, applied to the symbolforming resistors $1, $2 and 33 are instrumental in bringing thejunction 91 to this fifteen volt negative potential. With the previouslymentioned inversion, it can be seen I that the signal resulting fromthis potential is applied as a positive deflecting voltage to the platei 2 whereby the electron beam is deflected upwardly to the tophorizontal row pictured in FIGURE 3.

Concomitantly with the foregoing deflection is the ap plication of thesignal from section T1 to the second inputs of the AND gates 64 and 65.Due to the fact that the sustained or continuing signal from channel 32is simultaneously being impressed on the first inputs of these two gates64 and 65, it can be appreciated that both the OR gates '77 and 78 eachhave one of their inputs energized with the consequence that a negativeten volts is applied to the symbol forming resistors 87 and 88-. Inother words, both OR gates '77 and 78 are turned on and the junction 93is thereby brought to a minus ten volts. When inverted and applied tothe deflecting plate 1%, this causes a deflection of the electron beamto the right hand column appearing in FIGURE 3.

By reason of the combined vertical and horizontal defiection of theelectron beam, the beam is positioned at Pl, the upper right hand cornerof the region 133 presented in FIGURE 3.

The pulse from the resynchronization circuit 42 which triggers thesection Til into action can be quite short, a pulse on the order of only0.2 ,usec. being contemplated. Likewise, it is planned that thesuccessive triggering of the various sections of the timing chain takeplace at comparable intervals. Thus, it can be seen that while theelectron beam starts out at P1 it Will remain there for only a veryshort interval of time.

Next, the beam of electrons is deflected to P2. This occurs when sectionT2 is energized. The signal from section T2 is applied to what has beentermed the second input of certain AND gates. More specifically, the ANDgates brought into operation at this moment are the gates 52, 54, 56 and63. This is by reason of the sustained signal arriving via the channel32 being applied to the first inputs of these AND gates.

It will be noted that the AND gates 52, 54 and 56 are paired with gates51, 53 and 55, these latter gates being the ones activated in thereaching of P1. However, outputs from the gates 52, 54 and 56 serve thesame function, that of energizing an input of each OR gate 71, 72 and'73. This results in the maintenance of the junction 91 at the samepreviously mentioned minus fifteen volts.

Although there is no change in the potential developed at junction 91,there is a change in the potential estab lished at junction 93 under theinstant circumstances. This stems from. the fact that only the OR gate'77 is turned on. As can be discerned from the drawing, this h is byvirtueof the fact that the T2 signal is applied to the second input ofjust gate 63; the signal is not impressed on the gate 65 pairedtherewith. Hence, a potential of minus ten volts, this voltage havingbeen selected as previously mentioned, is applied to only the symbolforming resistor 87, the absence of a potential to the resistor 88causing the potential at junction 93 to be halved, i.e. reduced to minusfive volts owing to the shunt relation of resistors 87 and $8.

The net result is that the beam of electrons is moved to position P2. Atthis time it can best be brought out that a capacitive effect isinherent in a deflection system of the type with which we are currentlydealing. Stated somewhat differently, the particular deflection platecircuitry to which a deflecting voltage is applied Via any one of thejunctions 91-94 represents a capacitor which must be charged ordischarged when any of the elements 71-73 switch state. The timeconstant of this charging path is determined by the value of theresistors 81%. Advantage is made of this capacitive effect in thepresent instance to adjust the time constant so that the symbolsdisplayed on the face 1% of the cathode ray tube 96 will be comprised ofuniform lines rather than a series of spaced dots. While other circuitconstants enter into the picture, it might be mentioned that resistorsS19il having 2,000 ohm values have proved satisfactory. Accordingly,when the beam of electrons moves from P1 to P2, as it will do for thesucceeding positions, the capacitive effect causes the beam to sweepfrom the first position to the second rather than make an abrupt jump.In this way the transition from position to position is smooth and aWell defined symbol having excellent continuity is found, even thoughthe deflecting voltages themselves are abruptly modified in discreteincrements.

Having explained how the electron beam is moved to position P2, suchexplanation should be adequate to illustrate the manner in which theremaining positions PS-P17 are reached. Nonetheless, specific mentionwill be made of the next to last position P16. As shown in the drawingthe section T16 is connected to the second inputs of AND gates 58, 6d,62 and 68. Inasmuch as channel 32 is connected to the first inputs ofthese gates, it follows that the electron beam is deflected to thelowermost row of the matrix pictured in FIGURE 3. This is because theabove-mentioned AND gates turn the OR gates '74, '75 and 76 on, therebyapplying the full minus fifteen volts to the junction 92.

it can be seen, though, that the second input of only AND gate 65 isenergized, which together with the connection of the first input of thisAND gate to the channel 32 results in just the OR gate 79 beingenergized. The OR gate 89 at this time remains in its 01f condition, asit receives no input from either AND gate 6% or 76. Therefore, onlyminus five volts are applied to the junction 94, to produce the desiredhorizontal deflection of the electron beam. The combined vertical andhorizontal deflection causes the electron beam to he moved to thedesired position P16.

The last position in the painting of the numeral 5 is P17. In additionto the moving of the electron beam to this position, provision is madefor transmitting a signal back to the computer output register 10, whichin some instances is desirable in order to inform the computer that itcan proceed with the displaying of the next symbol or the handling ofother matters. Of course in a number of situations the computer will nothave the succeeding data ready and the resume signal will not benecessary, for when the succeeding information is ready the displaysystem will have concluded the presentation procedure of the symbol athand. Obviously, if a symbol is in the process of being painted, eventhough the total time is very short, one would not want the displayprocedure to be interrupted. In this regard, it should be remembcredthat the timing device is intended to operate at 0.2 microsecondintervals so the complete numeral will be displayed in only 3.4microseconds and even quicker if the intervals are shorter. At any ratethe point to be made is that through the agency of the AND gate 166,which has one input tied to the section T17 and its other input tochannel 32, the line 170 will be energized so as to provide a resumesignal if such is needed.

More importantly is the fact that the AND gate 166 supplies a signal tothe unblanking circuit 164 signifying that the circuit 164 should betriggered back to its blanking state.

Assuming that the next symbol to be displayed is the numeral 1 and thatthis symbol is to appear immediately to the right of the numeral 5 asillustrated in FIGURE 2, the general location of this symbol will bedetermined by signals transmitted to the mixers 110-116 from theregister 19 via the converters 118 and 122. Other than the generaldeflection, it can be seen that no successive horizontal deflection isneeded, for the electron beam only has to be moved in successive stepsthrough a vertical path to produce the number 1.

Referring to FIGURE 3 to illustrate the sequence of A, events, althoughthese steps need not be described in complete detail because of theinformation already presented, it can be pointed out that the electronbeam would start a at what has been labeled P3, then move to theposition i directly thereunder, then to the position directly above P19,then to P19, then to the position immediately under P19, then to theposition immediately above P and finally to what has been denoted asP15. Therefore, no potentials are needed at junctions 93 and 94.

However, minus fifteen volts will be needed .to produce the firstposition in the painting of the symbol 1. To accomplish this, section T1would be connected to the second inputs of AND gates 52, 5d and 56.Likewise, channel 24 would be connected to the first inputs of theseparticular gates. In this way when a signal is received from sect-ionT1, the OR gates 71, 72 and 73 are switched on to apply a minus fifteenvolt potential to junction 91. Hence, the electron beam will initiallyimpinge on the area 162 that has been labeled P3 in FIGURE 3, althoughit is of course the first position in the generation of the numeral 1.

The second position in forming numeral 1 would be produced by applying anegative potential of ten volts to junction 91. This is done byconnecting section T2 to the second inputs of two of the AND gates 51,53 and 55, for instance gates 51 and 53. With channel 24 connected tothe first inputs of these gates, the OR gates 71 and 73 will be turnedon to apply the desired potential to the junction 91. Under thesecircumstances OR gate '73 is left in its ofi condition.

The third position in the production of the numeral 1 would be effectedwith zero bolts on the junction 91, as well as no potential on the otherjunctions 92-94.

The seventh position, which will complete the display of the numeral 1,will be produced by applying a nega tive fifteen volt potential tojunction 92. Such action will be inaugurated by the forwarding of asignal from section T 7 While the production of this last deflection isdeemed readily apparent from what has already been said, it should beexplained that an AND gate corresponding to the AND gate 166 would haveone input connected to section T7 and its other input to channel 24. Notonly does such an AND gate supply a resume signal, if desired, but italso transmits a signal to the unblanking circuit 164 signifying the endof the numeral 1" display. The electron beam is accordingly blankeduntil section 1 is again energized in the initiation of another symbol,ay, the numeral 4 which is depicted at top center in IGURE 2.

It will be understood, it is believed, that to supply ll the elementsand connections necessary to present just be number of different symbolsdisplayed in FIGURE 2 ould unduly encumber the drawings. In practice,even ore symbols would be displayed. However, the needed 1i) wiring ofelements is not at all objetionable because of the speed and reliabilityof operation that is realized.

Having presented the preceding information, the general manner offorming desired symbols and the way in which they are generally locatedon the screen 109 of the cathode ray tube 96 should be manifest.Obviously, the invention is not limited to any particular symbols, asothers can beformed by using the appropriate number of components in themaking up of the logic elements associated with each junction 91, 92, 93and 94.

Possibly further description will be heIpfuL'though, in understandinghow the size of symbols can be varied. Since it has been explained thatthe particular potential applied to any junction 91, 92, 93 or 94governs the degree of deflection of the electron bemn, any controlledchange in the potential at these points will in fluence the extent ofdeflection. Hence, through the proper selection of values for theresistors 151, 152, 153 and 154 the connection of these resistors, if oflow enough resistance, to ground by the OR gate when it is on willreduce whatever potential that has been applied to the junctions 91, 92,93 and 94. A corresponding reduction will therefore ensue with respectto the deflection potentials applied to the electrostatic plates192-198. The end result is that the displayed symbols will be smaller,because the electron beam is not deflected as much. It will berecognized that the OR gate 159 may be turned on and off to produce afluctuating symbol size. Such a situation would prove of benefit, as oneillustration, where it is desired to attract the operators attention towhat is then taking place on the screen 1%.

By the same token, the actual potential at the junctions 91-94 can bealtered by means of the otentiometers 156, 157, 158 and 159. Forexample, with the resistance of the paired potentiometers reduced, thevoltage values at junctions 91 and 92 will be less than they otherwisewould be. The result is that the potentials applied to the verticaldeflecting plates 192, 104 will be lessened. The symbol then will not beas tall as before, although the symbol width will remain unchangedunless the setting of the paired potentiometers 158, 159 is modified.

Sufiicient information has probably already been given by which the roleplayed by the converter 142 can be understood. All that any signalcoming from the converter 142 does is to influence the biasing of theelectron gun 98 by way of the conventional video amplifier 1 56. Thus,whenever it is desired to paint a faint symbol this can be done, or ifan extra heavy outline is desired such can be accomplished.

One point to be stressed is that a practising of the present inventionis not dependent upon the design and manufacture of special components.All of the individual components comprising our system are currentlyavailable on the market. It is the manner in which these com ponents areWired and employed that presents an unique and highly versatile systemfor rapidly displaying characters of various descriptions. The symbolform to be displayed can be that most easily grasped by those personsresponsible for analyzing the encoded data. It might be explained, too,that reference to the computer output register 10 as the source ofencoded data is only illustrative, although the invention does perhapsfind its greatest utility where high-speed read-out is required. Thepoint to be made, though is that the source of coded information doesnot have to be a computer register.

As many changes could be made in the above construction and manyapparently widely different embodiments of the invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the followingclaims is intended to cover all of the generic and specific features ofthe invention herein described and all statements of the scope of theinventionwhich, as a matter of language, might be said to falltherebetween.

What is claimed:

1. A system for displaying coded information in the form of visuallyrecognizable symbols, the system including a source of digitally encodeddata to be converted to symbol form, a cathode ray tube including afluorescent screen at one end, an electron gun at the other end, meansconnected in circuit with said electron gun for directing anuninterrupted beam of electrons onto said screen, said beam being ofsubstantially uniform intensity, means for deflecting said beamvertically and means for deflecting said beam horizontally, a firstgroup of symbol forming resistors of equal ohmic value joined togetherat one end, means connecting said joined ends to said verticaldeflecting means, a second group of symbol forming resistors of equalohmic value joined together at one end, means connecting the joined endsof said second group of resistors to said horizontal deflecting means,and a plurality of digital logic elements responsive to discrete voltagesignals derived from said source for successively and uninterruptedlyapplying a given potential to various of the other resistor ends of bothgroups to provide an uninterrupted trace in accordance with the symbolthat is to be produced on said screen so that said symbol will beindicative of the encoded data.

2. A system for displaying coded information in the form of visuallyrecognizable symbols, the system including a source of digitally encodeddata to be converted to symbol form, a cathode ray tube including afluorescent screen at one end, an electron gun at the other end, meansconnected in circuit With said electron gun for directing a beam ofelectrons onto said screen, said beam being of uniform intensity, meansfor deflecting said beam vertically and means for deflecting said beamhorizontally, a first group of symbol forming resistors of equal ohmicvalue joined together at one end, means connecting said joined ends tosaid vertical deflecting means, a second group of symbol formingresistors of equal ohmic value joined together at one end, meansconnecting the joined ends of said second group of resistors to saidhorizontal deflecting means, a first group of OR gates having two inputsand and output for applying a given potential to any of the otherresistor ends belonging to said one group, a pair of AND gatesassociated with each of said OR gates, each AND gate having first andsecond inputs and an output, the outputs of each pair of AND gates beingconnected to the inputs of the OR gate with which said pair of AND gatesis associated, a second group of OR gates having two inputs and anoutput for applying a given potential to any of the other resistor endsbelonging to said second group, a pair of AND gates associated with eachof the OR gates in said second group, each AND gate in this lattersituation also having first and second inputs and an output, the outputsof each pair of AND gates in this latter situation being connected tothe inputs of the OR gate with which said pair of AND gates in thislatter situation is associated, timing means for applying a series ofsuccessive signals to certain of the first inputs of the AND gatesassociated with both groups of OR gates, and means controlled by saidsource for applying sustained signals to certain of the second inputs ofthe AND gates associated with both groups of OR gates, wherebycoincidence of signals on predetermined AND gates associated With bothgroups of OR gates will deflect the electron beam smoothly and directlyfrom position to position on the fluorescent screen to produce anuninterrupted trace forming symbol representative of the encoded data.

3. A system in accordance with claim 2 including means associated withsaid respective deflecting means for determining the region of saidscreen at which said symbol will be formed.

4. A system in accordance with claim 2 including additional means formodifying the respective potentials at the joined ends of said resistorsso as to alter the size of said symbol.

5. A system in accordance with claim 2 including means associated withsaid electron beam for modifying the beams intensity from one level ofuniformity to another.

References Cited in the file of this patent UNITED STATES PATENTS2,394,196 Morgan Feb. 5, 1946 2,594,731 Connolly Apr. 29, 1952 2,728,906Rea Dec. 27, 1955 2,766,444 Sheftelman Oct. 9, 1956 2,784,251 Young Mar.5, 1957 2,830,285 Davis Apr. 8, 1958 2,840,637 McNaney June 24, 19582,889,547 Wesley June 2, 1959 2,902,684 Mork Sept. 1, 1959 2,931,022Triest Mar. 29, 1960 3,024,454 Chaimowicz Mar. 6, 1962 3,047,851Palmiter July 31, 1962

1. A SYSTEM FOR DISPLAYING CODED INFORMATION IN THE FORM OF VISUALLYRECOGNIZABLE SYMBOLS, THE SYSTEM INCLUDING A SOURCE OF DIGITALLY ENCODEDDATA TO BE CONVERTED TO SYMBOL FORM, A CATHODE RAY TUBE INCLUDING AFLUORESCENT SCREEN AT ONE END, AN ELECTRON GUN AT THE OTHER END, MEANSCONNECTED IN CIRCUIT WITH SAID ELECTRON GUN FOR DIRECTING ANUNINTERRUPTED BEAM OF ELECTRONS ONTO SAID SCREEN, SAID BEAM BEING OFSUBSTANTIALLY UNIFORM INTENSITY, MEANS FOR DEFLECTING SAID BEAMVERTICALLY AND MEANS FOR DEFLECTING SAID BEAM HORIZONTALLY, A FIRSTGROUP OF SYMBOL FORMING RESISTORS OF EQUAL OHMIC VALUE JOINED TOGETHERAT ONE END, MEANS CONNECTING SAID JOINED ENDS TO SAID VERTICALDEFLECTING MEANS, A SECOND GROUP OF SYMBOL FORMING RESISTORS OF EQUALOHMIC VALUE JOINED TOGETHER AT ONE END, MEANS CONNECTING THE JOINED ENDSOF SAID SECOND GROUP OF RESISTORS TO SAID HORIZONTAL DEFLECTING MEANS,AND A PLURALITY OF DIGITAL LOGIC ELEMENTS RESPONSIVE TO DISCRETE VOLTAGESIGNALS DERIVED FROM SAID SOURCE FOR SUCCESSIVELY AND UNINTERRUPTEDLYAPPLYING A GIVEN POTENTIAL TO VARIOUS OF THE OTHER RESISTOR ENDS OF BOTHGROUPS TO PROVIDE AN UNINTERRUPTED TRACE IN ACCORDANCE WITH THE SYMBOLTHAT IS TO BE PRODUCED ON SAID SCREEN SO THAT SAID SYMBOL WILL BEINDICATIVE OF THE ENCODED DATA.